Visible crew/equipment: When Darkman swings on the wire to save Julie, you can see a large wire coming out of his shirt to support his weight, and you can make out several large wires holding Julie in the shot of her being grabbed.
Continuity mistake: At the hospital, when the doctor talks about Peyton's injuries, note that in front of him stands a group of doctors with a medicine cabinet behind them. When Peyton escapes and they all return to the room, the cabinet has been replaced by a window.
Answer: It's just psychedelic imagery to try and show his fragile state of mind and how he's losing it. The shattering light-bulb is likely to show that his mind is "shattering" (as light-bulbs appearing above someone's head are often used to signify brains/ideas in fictional, particularly cartoons), and the marionette "dancing" is the first part of the recurring motif in which he sees himself as a "freak." (Which is paid off later when he starts singing a demented song about "Paying five bucks to see the dancing freak!").